Mastersizer 2000 laser diffraction particle analyzer

Soil pH was determined at a ratio of 1:2.5 (soil to water, w/v). Soil moisture (SM) was measured gravimetrically. Total nitrogen (TN) and total carbon (TC) were measured by direct combustion using an element analyser (Vario EL III, Langenselbold, Germany). Available phosphorus (AP) was measured using the Mo-Sb anti-spectrophotometry method after extraction using sodium bicarbonate solution. Available nitrogen (AN) was measured through the alkaline hydrolysis diffusion method [25 (link)]. After acid dissolution, total phosphorus (TP) was measured using Mo-Sb colorimetry method. Soil texture was analysed using a Mastersizer 2000 Laser Diffraction Particle Analyzer (Malvern Instruments, Malvern, UK). The soil particle size was partitioned into clay (0–2 μm), silt (2–50 μm), and sand (50–2000 μm) according to the classification system of the US Department of Agriculture. We used iButton (1922L, supported by Maxim Integrated, San Jose, CA, USA), set to record temperatures automatically each hour. The thermometers were deployed in all 42 plots at the same time and were buried at a depth of 10 cm into the ground so as to decrease the occurrence of extreme values and skewed data. The daily average soil temperature during the sampling period was calculated using the data recorded by the button thermometer.